I would like to know how to render a 3D cylinder into this 2d line art style
Here is one way:
Render your scene

Using a completely transparent material, so that only the background color shows

with an orthographic camera, to remove perspective and make it like a diagram

Using Freestyle to draw the lines.
First, the material. This will be in blender internal, not cycles. Just make a normal material, turn on transparency, and turn the alpha to zero. This will make the object completely invisible. You can set the background color by changing the &quot;Horizon Color&quot; in the World tab in the Settings window.



To render with an orthographic projection, as used in diagrams and blueprints, change the projection type on your camera object:

And finally, to draw the lines, first turn on freestyle: there's a checkbox at the bottom of the Render tab of the Settings window. The default settings will create lines at the creases of your object and around the silhouette. To also draw the occluded lines, like the back bottom half of the cylinder, turn off the &quot;visibility&quot; selection criteria for your freestyle line (render layers tab of the properties window):